In a conventional lithographic printing press, ink or an ink emulsion is supplied to a high speed or slow speed drum using an ink supply system. As is known in the art, the ink is typically transferred to a plate cylinder via a number of intermediate drums or cylinders. Typically, a printing press includes a number of ink rail assemblies, with at least one ink rail assembly for each high speed or slow speed ink supply drum. Thus, the ink may be supplied to each of the ink rail assemblies through a system of supply lines and/or headers. The ink supply system generally includes a pump, a supply line, and a control valve. The ink supply system supplies ink under controlled pressure to an ink rail assembly, which is mounted closely adjacent to the high speed or slow speed ink supply drum. The ink rail assembly generally includes an ink rail having a number of orifices or ink keys spread out along its length. Thus, ink is supplied to the ink keys of the ink rail, from which the ink is applied directly to the surface of the high speed or slow speed drum.
In general, ink flow control is effected by ink pulses of variable duration corresponding to the printing density requirement of a given printed column. Accordingly, the ink supply system includes a cycling mechanism that turns the ink supply “on” for a period of time and “off” for a period of time. One cycling mechanism is dedicated to one inking column. As shown in FIG. 1, a conventional ink rail assembly 10 includes an ink rail 12 with ink keys 14 evenly spaced along the ink rail 12 and one or more ink metering assemblies, for example, page packs 16. The page packs 16 are in fluid communication with the ink keys 14. Each ink key 14 is fluidly coupled to a dedicated ink supply outlet (not shown) on the page pack 16. Only one ink key 14 is supplied by each ink supply outlet on the page pack 16. For example, in order to supply 20 ink keys, two page packs each having 10 supply outlets would be required. The cycling mechanism can be a valve disposed near the ink outlet of the page pack. The valve is moveable between an open and closed position to control the flow of ink into the ink rail 12.